The semiconductor industry has progressed into nanometer technology process nodes in pursuit of higher device density, higher performance, and lower cost. Despite groundbreaking advances in materials and fabrication, scaling planar device such as the conventional MOSFET has proven challenging. As merely some examples, deposition techniques, etching techniques, and other processes that circulate liquids, gasses, or plasmas across device features perform well when the features are widely spaced and accessible to the ambient reactants. However, narrow high-aspect ratio trenches and cavities restrict circulation and reduce the amount of reactants available within the trench. This may cause uneven deposition or etching within the trench.
To further push the state of the art, circuit designers are looking to novel structures to deliver improved performance. One avenue of inquiry is the development of three-dimensional designs, such as a fin-like field effect transistor (FinFET). A FinFET can be thought of as a typical planar device extruded out of a substrate and into the gate. A typical FinFET is fabricated with a thin “fin” (or fin structure) extending up from a substrate. The channel of the FET is formed in this vertical fin, and a gate is provided over (e.g., wrapping around) the channel region of the fin. Wrapping the gate around the fin increases the contact area between the channel region and the gate and allows the gate to control the channel from multiple sides. This can be leveraged in a number of way, and in some applications, FinFETs provide reduced short channel effects, reduced leakage, and higher current flow. In other words, they may be faster, smaller, and more efficient than planar devices.
However, FinFETs and other nonplanar devices have even more complicated geometries and may have more high-aspect ratio trenches to fill. Accordingly, while conventional techniques for device fabrication have been adequate in some respects, they have been less than satisfactory in others. In order to continue to meet ever-increasing design requirements, further advances are needed in device fabrication and other areas. The present disclosure provides improvements that relate to the fabrication of planar devices as well as FinFETs and other nonplanar devices.